WO2007132708A1

WO2007132708A1 - Aluminum electrolytic capacitor

Info

Publication number: WO2007132708A1
Application number: PCT/JP2007/059584
Authority: WO
Inventors: Hisao Nagara; Kazunari Imamoto; Shigetaka Furusawa; Hiroyuki Matsuura
Original assignee: Panasonic Corporation
Priority date: 2006-05-15
Filing date: 2007-05-09
Publication date: 2007-11-22
Also published as: TWI402875B; CN101443865B; JP2007305899A; CN101443865A; US20090207557A1; TW200809886A; US7990681B2

Abstract

A high-capacity, long-life and low-ESR aluminum electrolytic capacitor having excellent short-circuiting resistance is provided. The aluminum electrolytic capacitor is provided with a capacitor element wherein a first separator, a cathode foil and a second separator are wound by being successively placed one over another. The capacitor element is impregnated with a driving electrolytic solution and is stored in a metal case, then, an open end of the metal case is sealed with a sealing material. A ratio of B/A is set at 0.5-0.8, wherein, A is the total of the thicknesses of the first and the second separators prior to winding, and B is the total of the thicknesses of the first and the second separators after winding.

Description

Specification

Aluminum electrolytic capacitor

Technical field

[0001] The present invention relates to an aluminum electrolytic capacitor used in various electronic devices.

Background art

[0002] Fig. 2 shows the configuration of a conventional aluminum electrolytic capacitor. This figure is a partially cutaway perspective view showing an anode foil 11 in which a dielectric oxide film is formed by chemical conversion on the surface of an aluminum foil whose effective surface area is enlarged by etching, and a cathode in which the aluminum foil is etched. Capacitor element 19 is formed by winding foil 12 through separator 13. In this capacitor element 19, an anode lead wire 15 and a cathode lead wire 16 are connected to the anode foil 11 and the cathode foil 12, respectively, and impregnated with a driving electrolyte solution (not shown). At the same time, the capacitor element 19 is inserted into a metal case 18 such as an aluminum case and sealed with a sealing material 17 such as rubber to obtain a conventional aluminum electrolytic capacitor.

[0003] The separator 13 is made of cellulose fibers such as manila hemp, craft, hemp, and esbalt, and is properly used depending on the performance of the separator such as thickness and density.

[0004] The performance required for aluminum electrolytic capacitors is high capacity, low ESR (equivalent series resistance), and high reliability.

[0005] In recent years, with the progress of miniaturization and higher performance of digital circuits such as AV equipment and personal computers, higher capacity, lower ESR, and higher reliability of aluminum electrolytic capacitors have become important. In order to improve the ESR characteristics, the materials used for the separator, the thickness, etc., and the higher conductivity of the driving electrolyte are being studied.

[0006] As related prior art document information, for example, Patent Document 1 and Patent Document 2 are known.

[0007] However, if a low-density separator is used to improve ESR characteristics as in the case of a conventional aluminum electrolytic capacitor, the tensile strength of the separator is weakened, and the capacitor element is reduced. The separator may weaken due to the occurrence of breakage when it is turned and the stress of the anode lead wire and cathode lead wire connected to the cathode foil and the cathode lead wire part. is doing.

[0008] Further, when the thickness is increased at a low density in order to improve the strength of the separator, in addition to the deterioration of the ESR characteristics, the volume of the electrode foil per unit volume of the capacitor element is reduced, and as a result, the electrode Since the area of the foil is small, it is difficult to increase the capacity.

Patent Document 1: Japanese Patent Laid-Open No. 08-273984

Patent Document 2: Japanese Patent Laid-Open No. 2000-173862

Disclosure of the invention

[0009] The present invention provides an aluminum electrolytic capacitor that is excellent in short-circuit resistance and excellent in high-temperature reliability and has a high capacity and low ESR by solving such a conventional problem.

[0010] For this purpose, the present invention has a capacitor element in which an anode foil, a first separator, a cathode foil, and a second separator are sequentially stacked, and a driving electrolyte is applied to the capacitor element. An aluminum electrolytic capacitor that is impregnated and stored in a metal case, and then the open end of the metal case is sealed with a sealing material, and the total thickness A of the first and second separators before winding and the thickness after winding The ratio B / A of the total thickness B of the first and second separators is 0.5 to 0.8.

As described above, the aluminum electrolytic capacitor of the present invention is a ratio of the total thickness A of the first and second separators before winding to the total thickness B of the first and second separators after winding B / By setting A to 0.5 to 0.8, the rate of change in the total thickness of the separator before and after winding is small. Therefore, the stress due to the separator contact portion between the anode lead wire and cathode lead wire is suppressed, and short-circuit failure during capacitor element scraping and short-circuit failure during long-term voltage application at high temperatures can be reduced. It is an excellent one.

[0012] In particular, by using an acid component having an acid dissociation constant pKa of 5 to 9 as the electrolyte of the driving electrolyte, deterioration of the separator due to the acid component is suppressed particularly in a high temperature environment. . Therefore, high-temperature solder reflow during surface mounting, short-circuiting during high-temperature voltage application, lead wire corrosion, and increase in leakage current can be suppressed to improve reliability. The

[0013] In particular, an aprotic solvent is used as the main solvent of the driving electrolyte. As a result, the pressure rise due to moisture adsorbed on the driving electrolyte solution separator contained in the aluminum electrolytic capacitor can be suppressed, so that the stabilization of characteristics at high temperature is improved and the high temperature reliability is excellent. is there.

Brief Description of Drawings

FIG. 1 is a partially cutaway perspective view of an aluminum electrolytic capacitor of the present invention.

FIG. 2 is a partially cutaway perspective view of a conventional aluminum electrolytic capacitor.

Explanation of symbols

[0015] 1, 11 Anode foil

2, 12 Cathode foil

3a, 3b, 13 separator

5, 15 Anode lead wire

6, 16 Cathode lead wire

7, 17 Sealing material

8, 18 metal case

9, 19 Capacitor element

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an aluminum electrolytic capacitor of the present invention will be described with reference to an embodiment and drawings.

FIG. 1 is a partially cutaway perspective view of an aluminum electrolytic capacitor according to an embodiment of the present invention.

In FIG. 1, an anode foil 1 is formed by forming a dielectric oxide film with an anodic oxide film on the surface of an aluminum foil whose etching has increased the effective surface area. Further, a cathode lead wire 6 for drawing is connected to the cathode foil 2 obtained by etching the aluminum foil. Capacitor element 9 is configured by winding anode foil 1, first separator 3 a, cathode foil 2, and second separator 3 b in order. After impregnating the capacitor element 9 with a driving electrolyte (not shown), the capacitor element 9 is inserted into an aluminum metal case 8 and the opening of the metal case 8 is sealed with a sealing material 7. Yes.

[0018] The capacitor element 9 has a ratio B between the total thickness A of the first and second separators 3a and 3b before winding and the total thickness B of the first and second separators 3a and 3b after winding. / A force is wound so as to be 0.5 to 0.8.

[0019] When the ratio B / A is less than 0.5, stress is applied to the lead wire portion at the time of winding, and there is a high possibility that a short circuit will occur.

[0020] When the ratio BZA exceeds 0.8, the ESR characteristics deteriorate.

[0021] Therefore, the ratio BZA is desirably 0.5 to 0.8.

[0022] In order to make the ratio B / A 0.5 to 0.8, as described below, the type of separator, density, basis weight and scraping method, lead terminal shape, etc. We are trying to optimize. At this time, it is not necessary to distinguish between the first and second separators 3a and 3b. Hereinafter, the first and second separators 3a and 3b are collectively referred to simply as “separators”.

[0023] As the material of the separator, cellulose fiber, rayon fiber, polyethylene fiber, polypropylene fiber, nylon fiber, or the like can be used. In particular, when chemical fibers or regenerated fibers are used, non-hollow fibers that do not twist in the shape of the fibers are superior in short-circuit resistance and ESR characteristics, because the fibers are not easily crushed by compression during staking.

[0024] In the separator, the density range of the separator should be selected from 0 · 2 to! · Og / cm ³ so as not to obstruct the ion pathway of the driving electrolyte as much as possible. Is desirable. When the density of the separator is less than 0.2 g / cm ^3, the force S is more effective for the ESR characteristics S, and the insulation performance of the separator itself is lowered, so the short-circuit resistance cannot be further improved.

[0025] When the density of the separator exceeds 1. Og / cm ³ , the short-circuit resistance is further improved, but the ESR characteristics cannot be further improved.

[0026] Furthermore, the basis weight of the separator is expressed by the product of density and thickness, and the mechanical strength of the separator can be ensured by setting the basis weight in the range of 4 to 20 g / cm ² . Breaking at the time of picking can be suppressed, and short circuit resistance can also be improved. In addition, since the volume of the scraping element per unit volume of the capacitor can be increased, it is possible to hold a large amount of driving electrolyte, which is great for stabilizing the characteristics at high temperatures as well as increasing the capacity. It has an effect.

[0027] As the staking method, a jig having a curved shape is used as a staking start position so that excessive stress is not applied to the separator during staking. Furthermore, it is possible to adjust the stress at the time of cutting by controlling the cutting speed and tension by inverter control and load optimization.

[0028] Further, with respect to the shape of the lead terminal, it is possible to further improve the short-circuit resistance by using a curved shape that does not have an acute protruding portion on the end surface of the lead terminal. The shape of a lead terminal with an acute end face of 90 degrees, like a normal lead terminal, imposes excessive stress on the separator, resulting in poor short-circuit resistance.

[0029] As the electrolyte of the driving electrolyte, an acid component having an acid dissociation constant pKa of 5 to 9 is used. Examples of the acid component having a pKa of 5 to 9 include malonic acid, maleic acid, fumaric acid, phthalic acid, isophthalanolic acid, terephthalic acid, dimethylmaleic acid, and aminobenzoic acid. If an acid component with an acid dissociation constant pKa of less than 5 is used as the electrolyte for the driving electrolyte, the lead foil portion of the electrode foil undergoes a corrosion reaction due to acid during high-temperature solder reflow, and reliability decreases.

[0030] Further, when an acid component having an acid dissociation constant pKa of more than 9 is used as the electrolyte of the driving electrolyte, the electric conductivity is low because the ionization constant is small.

[0031] As the solvent of the electrolytic solution, an aprotic solvent, for example, ratatones (y petit ratatones, a valerolatatanes, γ valerolatatanes, etc.), carbonates (ethylene carbonate, propylene carbonate, diethylene carbonate, styrene carbonate, dimethylolate carbonate) Etc.), nitrile type (acetonitrile, 3-methoxypropionitryl etc.), furan type (2,5 dimethoxytetrahydrofuran etc.), sulfolane type (sulfolane, 3 methylsulfolan, 2,5_dimethylsulfolane etc.), ether type (Methylal, 1,2-Dimethoxyjetane, 1_Ethoxy_2-Methoxyethane, 1,2-Diethoxyethane, etc.), Amides (Ν Methylphenolamide, Ν, ジメチル -dimethylformamide, メチル Methylacetamide, メチル Methylpyrodirinone, etc.) But It is below. By using these solvents as the main solvent, low ESR and high temperature stability can be achieved.

[0032] Further, as the base component of the electrolyte, a tertiary amine compound, an imidazolium compound, an imi Examples include dazolinium compounds and pyridinium compounds. By using these base components, it is possible to increase the electrical conductivity and stabilize the characteristics at high temperatures.

Hereinafter, the present embodiment will be described in detail using examples.

[Example 1]

First, the surface of the aluminum foil was roughened by etching treatment, and then anode foil 1 (thickness 100 xm) made of aluminum foil formed with a dielectric oxide film (formation voltage 22 V) by anodic oxidation treatment was prepared. Anode foil 1 to which this anode lead wire 5 is connected, a first separator 3a made of cellulose fibers (thickness 40 xm, density 0.4 g / cm ³ ), and an anodized aluminum foil are etched and used for withdrawal. The cathode foil 2 (thickness 40 μm) to which the cathode lead wire 6 is connected and the second separator 3b (thickness 40 μm) are sequentially stacked and wound, whereby the capacitor element 9 is Obtained. The ratio of the total thickness A of the first and second separators 3a and 3b before winding to the total thickness B of the first and second separators 3a and 3b after winding is BZA, 0.5. . The lead tension is adjusted so that the ratio B / A is 0.5, and the lead terminal shape is a lead terminal with a curved surface so that there are no sharp protrusions on the end face of the lead terminal. Was used.

Table 1 shows a list of driving electrolytes used in the examples and comparative examples.

[0036] [Table 1] Composition of electrolyte for driving Acid dissociation constant

Solvent type

(Wt%) (pa)

γ-Ptylolactone (75) aprotic

A 8.40

Phthalic acid 1,2,3,4-tetramethylimidazolium (25) Solvent

γ-petit mouth outside (75)

Aprotic

B aminobenzoic acid 1,2,3,4- 6.79

Solvent 亍 Tramethylimida '/ Rinium （25）

γ-Butirola Extrane (75) Aprotic

C 4.86

Succinic acid 1,2,3,4- 亍 tramethylimita'no'linium (25) Solvent

γ-Butylora (75) Aprotic

D 9.24

Succinic acid 1,2,3,4- 亍 tramethylimidazolinium (25) Solvent

Ethylene gericol monomethyl ether (75) Protic

E 8.40

Phthalic acid 1,2,3,4-tramethylimita'zolinium (25) Solvent [0037] In Example 1, the driving electrolyte shown in Table 1 (75% by weight of γ-petit-mouth rataton and 25% by weight of 1,2,3,4-tetramethylimidazolium phthalate) ^_0/0) was used to impregnate the capacitor element 9. The acid dissociation constant pKa of this driving electrolyte is 8.40. Next, the capacitor element 9 is inserted into a bottomed cylindrical aluminum metal case 8, and the opening of the metal case is sealed by a curling process with a sealing material 7 made of resin vulcanized butyl rubber. An aluminum electrolytic capacitor was produced.

[0038] (Example 2)

In Example 1, the ratio B / A between the total thickness A of the first and second separators 3a and 3b before winding and the total thickness B of the first and second separators 3a and 3b after winding is 0. An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the value was changed to 65.

[0039] (Example 3)

In Example 1, the ratio B / A between the total thickness A of the first and second separators 3a and 3b before winding and the total thickness B of the first and second separators 3a and 3b after winding is 0. An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the value was changed to 80.

[0040] (Example 4)

In Example 1, the electrolyte for driving shown in Table 1 (75% by weight of γ-petit latatotone, 25% by weight of aminobenzoic acid 1, 2, 3, 4-tetramethylimidazolium, An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the dissociation constant pKa was 6.79).

[0041] (Comparative Example 1)

In Example 1, the winding tension is relaxed, and the separator density is 1. Og / cm ³ , the total thickness A of the first and second separators 3a and 3b before winding, and after winding An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the ratio B / A of the total thickness B of the first and second separators 3a and 3b was 0.85.

[0042] (Comparative Example 2)

In Example 1, a sharp terminal shape is used for the lead terminal, the total thickness A of the first and second separators 3a and 3b before winding, and the first and second separators 3a and 3b after winding. An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the ratio B of total B was set to 0.45. [0043] (Comparative Example 3)

In Example 1, the electrolyte solution for driving shown in Table 1 (75% by weight of y-petit-mouth rataton, 25% by weight of oxalic acid 1,2,3,4-tetramethylimidazolium, acid dissociation constant pKa Were used in the same manner as in Example 1 except that 4.86) was used.

[0044] (Comparative Example 4)

In Example 1, driving electrolyte shown in Table 1 D ₍₇ _ Petit port Rataton 75 wt%, co Haq acid 1, 2, 3, 4-tetramethyl imidazolinium two © beam 25 wt%, acid dissociation An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the constant pKa was 9.2 4).

[0045] (Comparative Example 5)

In Example 1, the electrolyte solution for driving E shown in Table 1 (75% by weight of ethylene glycol monomethyl ether and 25% by weight of 1,2,3,4-tetramethylimidazolium phthalate) An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the acid dissociation constant pKa was 8.40). Ethylene glycol monomethyl ether is a protic solvent

[0046] The above Examples:! ~ 4 and Comparative Example:! ~ 5 Aluminum Electrolytic Capacitors, 20 each, were fabricated, their initial characteristics and life test (105 ° C, 16V load, 2000 hours) and high temperature solder reflow A test was conducted. The results are shown in Table 2. The size of the aluminum electrolytic capacitor was 10 mm in diameter and 10 mm in length, the rated voltage was 16 V, and the capacitor design was such that each capacitor element had the same porosity. A ripple load test was conducted at a test temperature of 105 ° C.

[0047] [Table 2]

105-C16V load sensor center characteristics Initial characteristics High S Solder 7 After

Thickness after 2000 hours of electrolyte

Acid dissociation constant Solvent type Capacity Volume

Ratio

pKa Capacity ESR ■> a-h ESR 3 -G ESR short (B / A) Change rate Change rate

tmQ) Number of occurrences (mQ) Number of occurrences (mQ) Number of occurrences β

(%) (%)

Examples aprotic

0.5 8.40 471 45 0 -3 46

1 0 -13 50 0

Solvent

Examples Aprotic

0.65 8,40 512 44 0 -3 45 0 -13 51 0

2 Solvent

Example

0.8 8,40 532 44 0 -3 45 0 -12 50 0 3

Example Non-P

0.5 6.79 470 50 0 -4 51 0 -13 55 0 4 Solvent

Comparative example Non-zlotonicity

0.85 8.40 541 68 0 -5 69 0 -20 73 0 1 Solvent

Comparative example

0.45 8,40 459 42 3 -5 44 5 -22 55 7 2 Solvent

Comparative example

0.5 4,86 471 40 0 -9 52 2 -31 66 5 3 Solvent

Comparative example

470 84 0 -4 89 0 -15 99 0 4 0.5 9.24

Solvent

Ratio ¾ Example Protic

0.5 8.40 471 44 0 -10 76 0 -41 132 0 5 Solvent

π = 20 β

[0048] As is apparent from Table 2, in the aluminum electrolytic capacitors of Examples 1 to 4, the ratio of the total thickness セ of the separator before winding to the total thickness of the separator after winding Β / Α is 0. It can be seen that by using the materials of 5 to 0.8, the initial characteristics, the characteristics after high-temperature solder reflow, and the characteristics after the life test (high temperature degradation characteristics) are superior to those of Comparative Examples 1 to 5.

[0049] In the aluminum electrolytic capacitor of Comparative Example 1, since the ratio BZA of the total thickness of the separator was larger than 0.8, the initial characteristics and the life characteristics were greatly deteriorated. It can be seen that the aluminum electrolytic capacitor of Comparative Example 2 has a short terminal incidence because the ratio B / A of the total thickness of the separator is less than 0.5 and has an acute terminal shape.

[0050] In addition, in the driving electrolytic solution having an acid dissociation constant pKa of less than 5 as in the aluminum electrolytic capacitor of Comparative Example 3, the deterioration of the separator due to the acid is increased, so that the high temperature solder reflow and the short circuit resistance after the life test Becomes worse. On the other hand, the drive electrolyte with an acid dissociation constant pKa greater than 9 as in the aluminum electrolytic capacitor in Comparative Example 4 has a low ESR characteristic because the conductivity of the drive electrolyte is low. Power.

[0051] Further, in the aluminum electrolytic capacitor of Comparative Example 5, since the protic solvent is used as the driving electrolyte, the thermal stability is deteriorated, and thus the capacitor characteristics are deteriorated in the high-temperature solder reflow and the life test. I understand that. [0052] As described above, the aluminum electrolytic capacitor of the present invention includes the total thickness A of the first and second separators 3a and 3b before winding, and the first and second separators 3a and 3b after winding. When the ratio B / A of the total thickness B is 0.5 to 0.8, the change rate of the separator thickness before and after winding is small. Therefore, stress due to the separator contact portion of the anode lead wire 5 and the cathode lead wire 6 is suppressed, and an aluminum electrolytic capacitor excellent in short-circuit resistance, ESR characteristics, and high-temperature reliability can be realized.

Industrial applicability

[0053] The present invention is an aluminum electrolytic capacitor having excellent short-circuit resistance, high capacity, long life, and low ESR characteristics, and demands for miniaturization and high performance of digital circuits such as AV equipment and personal computers. It can correspond to.

Claims

The scope of the claims

[1] A capacitor element in which an anode foil, a first separator, a cathode foil, and a second separator are sequentially stacked and wound,

After impregnating the capacitor element with the driving electrolyte and storing in the metal case, the open end of the metal case is sealed with a sealing material,

The ratio B / A between the total thickness A of the first and second separators before winding and the total thickness B of the first and second separators after winding was set to 0.5 · 0 · 8. This is an aluminum electrolytic capacitor.

[2] The aluminum electrolytic capacitor according to claim 1, wherein an acid component having an acid dissociation constant pKa of 5 to 9 is used as the electrolyte of the driving electrolyte.

[3] The aluminum electrolytic capacitor according to claim 2, wherein an aprotic solvent is used as a main solvent of the driving electrolyte.

[4] The density of at least one of the first separator and the second separator is 0.2.

The aluminum electrolytic capacitor according to claim 1, which is in a range of ˜1. Og / cm ³ .

[5] Basis force of at least one of the first separator and the second separator ¾ to 2

The aluminum electrolytic capacitor according to claim 1, which is in a range of Og / cm ² .

[6] A contact surface between the anode foil and the first or second separator of the anode electrode, further comprising an anode electrode connected to the anode foil and a cathode electrode connected to the cathode foil Is a curved shape,

2. The aluminum electrolytic capacitor according to claim 1, wherein a contact surface of the cathode electrode with the cathode foil and the first or second separator is also a curved surface.